Micro- and Nano-Mechanics of Active Biopolymer Networks

该奖项的研究目标是开发新的分析和数值方法来研究细丝力学和网络结构与半柔性网络集体弹性特性的复杂关系。半柔性网络是刚性聚合物交联的聚集体。它们与现代合成化学通常的产物——聚合材料有着根本的不同。在外加应力作用下，半柔性网络可以将弹性能量存储在组成的细丝的拉伸和弯曲中，而传统的聚合物网络是由高度柔性的聚合物链组成的，只能将弹性能量存储在细丝的拉伸中。半柔性网络最常见的例子存在于活细胞的细胞骨架中。在那里，坚硬的蛋白丝（f -肌动蛋白）交联形成一个承受压力的框架，使细胞具有机械刚性。最近的实验表明，网络结构和分子马达动作的微小变化可以导致这些f -肌动蛋白网络弹性的显著变化。本研究将详细探讨这些网络结构和非平衡稳态的变化（通过分子马达的作用）如何导致网络的大力学变化。成功完成这项工作的好处之一将是对构建新型轻质机械可调材料的设计原则有更深的理解。该理论还将解决材料设计的新仿生方法，该方法利用内源性马达的作用，通过修改材料的非平衡稳态来调整机械性能。这样的研究将能够创造出新的生物相容性材料，其机械性能可以精确控制。这些材料可用于促进伤口愈合。最后，本研究将有助于培养从事物理、生物和工程界面工作的学生/博士后。

The research objective of this award is to develop new analytic and numerical approaches to examine the complex relationship of filament mechanics and network structure to the collective elastic properties of semiflexible networks. Semiflexible networks are cross-linked aggregates of stiff polymers. They are fundamentally different from the better understood polymeric materials that are the usual products of modern synthetic chemistry. Under applied stress semiflexible networks can store elastic energy in both the stretching and bending of the constituent filaments, while traditional polymer networks, which are composed of highly flexible polymer chains, store elastic energy only in filament stretching. The most common example of a semiflexible network is found in the cytoskeleton of living cells. There stiff protein filaments (F-actin) are cross-linked to form a stress-bearing framework that gives the cell its mechanical rigidity. Recent experiments have shown that small changes in network architecture and in the action of molecular motors can lead to significant changes the elasticity of these F-actin networks. This research will explore in detail how these changes in network structure and non-equilibrium steady-state (via the action of the molecular motors) leads to large mechanical changes of the network. Among the benefits of the successful completion of this work will be a deeper understanding of the design principles for building a new class of light-weight, mechanically tunable materials. The theory will also address new biomimetic approaches to materials design that use the action of endogenous motors to tune mechanical properties through the modification of the materials non-equilibrium steady-state. Such research will enable the creation of new bio-compatible materials whose mechanical properties can be precisely controlled. These materials may find applications in the promotion of wound healing. Finally, this research will assist the training of students/postdocs working at the interface of the physics, biology, and engineering.